JPH10303602A - Lamination band pass filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the small-sized lamination band pass filter with a small insertion loss. SOLUTION: At least two U-shaped strip line resonators 2, 3 whose one end connects to ground and whose other end is open are formed on a 1st dielectric layer 1, wide electrode sections 2e, 3e for forming capacitance are provided to the open ends of the U-shaped strip line resonators 2, 3 and the wide electrode sections 2e, 3e and the open ends of the U-shaped strip line resonators 2, 3 are connected with sufficiently thin connection electrodes 2d, 3d. Grounded capacitance electrodes 7, 8 opposite to an input electrode 5 and an output electrode 6 and the wide electrode sections 2e, 3e are formed on a 2nd dielectric layer 4, the input electrode 5 and the output electrode 6 are formed so as to cross the U-shaped part of at least any of the U-shaped strip line resonators 2, 3, the 1st dielectric layer 1 and the 2nd dielectric layer 4 are laminated and a dielectric layer is interposed between the 1st dielectric layer 1 and the 2nd dielectric layer 4 and an earth electrode 11 is laid out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer band-pass filter used for high-frequency devices, particularly mobile communication devices such as mobile phones.

[0002]

2. Description of the Related Art In recent years, mobile communication devices typified by mobile phones have shown rapid growth, and the miniaturization and weight reduction of the devices have been promoted. Accordingly, there is a demand for miniaturization and low loss of components used in equipment. Among these mobile communication devices, a band-pass filter is one of important components.

FIG. 7 shows an example of a conventional bandpass filter. This is described in JP-A-7-66605. The structure of this laminated bandpass filter will be described below.

On one surface of the first dielectric substrate 51, a ground electrode 52 is formed almost entirely, and on the other surface, two pattern electrodes 53, 54 facing the ground electrode 52 are formed.
Are formed. The pattern electrodes 53 and 54 are formed in a U-shape from the side to the inside, and are formed so that the width decreases toward the inside.
An adhesive layer 55 such as a polyimide layer is formed on the pattern electrodes 53 and 54. On this adhesive layer 55, a second dielectric substrate 56 is formed. On the second dielectric substrate 56, a shield electrode 57 is formed on almost the entire surface. Then, protective layers 58 and 59 are formed so as to cover the ground electrode 52 and the shield electrode 57.

Then, the U-shaped pattern electrode 53,
54 has input / output electrodes 53a and 54a on the side, and one ends 53b and 54b are connected to the ground. FIG. 8 shows an equivalent circuit of this conventional example. In this equivalent circuit, M indicates electromagnetic coupling.

FIG. 9 shows another example of a conventional bandpass filter. This is described in JP-A-8-8605. The structure of this laminated bandpass filter will be described below.

[0007] The shield electrode 7 is provided on one surface of the dielectric sheet 70.
The input / output coupling capacitance electrodes 77 and 78 and the loading capacitance electrode 7 are formed on one surface of the dielectric sheet 71 thereon.
9, an interstage coupling capacitance electrode 80 is formed, two strip line resonator electrodes 81 and 82 are formed on one surface of a dielectric sheet 72 thereon, and a dielectric sheet 71 and a dielectric sheet 73 are formed thereon. Similarly, the input / output coupling capacitance electrode 8
3, 84, a loading capacitance electrode 85, and an inter-stage coupling capacitance electrode 86 are formed, a shield electrode 87 is formed on one surface of a dielectric sheet 74 thereon, and a dielectric sheet 75 is laminated thereon. Have been. Then, input / output terminals 88 and 89 and ground electrodes 90 and 91 are formed on the side surfaces of the stacked body. And it constitutes a comb line filter.

[0008]

However, in the above configuration, when a large loading capacitance is to be obtained in order to reduce the size of the filter, the area of the loading capacitance electrode becomes large, and the insertion loss increases. Had. In addition, since the stripline resonator electrode is linear, it has been difficult to reduce the size to a certain degree or more. SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized laminated band-pass filter having a small insertion loss.

[0009]

According to the present invention, at least two U-shaped stripline resonators each having one end grounded and the other end open are formed on a first dielectric layer. On the open end side of the strip line resonator, there is a wide electrode portion for forming a capacitance, and the wide electrode portion and the open end of the U-shaped strip line resonator are connected by a connection electrode sufficiently thinner than them. An input electrode, an output electrode, and a grounded capacitor electrode facing the wide electrode portion are formed on the second dielectric layer, and each of the input electrode and the output electrode is provided with at least one electrode. Ground electrodes formed so as to cross the U-shape of the two U-shaped stripline resonators, stack the first dielectric layer and the second dielectric layer, and interpose dielectric layers above and below the first dielectric layer and the second dielectric layer. Is a laminated bandpass filter in which is disposed.

Further, in the present invention, two of the second dielectric layers are provided, and are disposed above and below the first dielectric layer on which the U-shaped stripline resonator electrode is formed.

According to the present invention, the wide electrode portion on the first dielectric layer and the capacitance electrode on the second dielectric layer face each other to obtain a predetermined capacitance. However, when the lamination shift occurs, the area of the facing electrode fluctuates, and it is expected that a predetermined capacity cannot be obtained. As a means for solving this, in the present invention, the first
Is connected between the wide electrode formed on the dielectric layer of the first embodiment and the open end of the U-shaped stripline resonator electrode by a connection electrode which is sufficiently thinner than them. The thin connection electrode portion is configured such that the boundary portion of the capacitor electrode on the second dielectric layer is opposed, thereby suppressing a change in capacitance in the event of stacking misalignment.

In the U-shaped stripline resonator according to the present invention, a stripline having one end grounded and a wide stripline having a lower characteristic impedance are connected by a stripline having a higher characteristic impedance than those. It is a U-shaped stripline.
Also, two U-shaped stripline resonators are opposed to each other with one end of the stripline grounded.

[0013]

FIG. 1 is an exploded view showing a laminated structure according to an embodiment of the present invention. FIG. 2 shows a strip line resonator pattern of this embodiment, FIG. 3 shows an input / output electrode pattern diagram, and FIG. 4 shows a perspective view.

In this embodiment, a plurality of dielectric layers are stacked. First, two strip line resonator electrodes 2 and 3 are formed on the first dielectric layer 1. The stripline resonator electrodes 2 and 3 have a U-shape, one end of which extends to the side surface of the dielectric layer 1, is grounded, and the other end is open. The U-shaped grounded sides are arranged in parallel so that the grounded sides face each other. The U-shaped stripline resonators 2, 3
Has wide electrode portions 2e and 3e for forming a capacitance on the open end side, and the wide electrode portions 2e and 3e and the U-shaped stripline resonators 2 and 3 have connection electrodes 2 that are sufficiently thinner than them.
d and 3d.

Next, an input electrode 5, an output electrode 6, and capacitance electrodes 7 and 8 are formed on the second dielectric layer 4. The input electrode 5 is a line electrode extending from the center of one side surface toward the center, and is arranged to cross one U-shaped stripline resonator electrode 2. Then, when viewed in a projected state in the state of being stacked, FIG.
, And has a structure that is overlapped on both the open side and the ground side of the U-shaped stripline resonator electrode 2. Similarly, the output electrode 6 is a line electrode extending from the center of one side surface toward the center.
The U-shaped stripline resonator electrode 3 is disposed so as to cross the same, and the U-shaped stripline resonator electrode 3 has a structure that overlaps on both the open side and the ground side. The input electrode 5 and the output electrode 6 have wide portions 5b and 6b at portions overlapping the open side of the U-shaped stripline resonator electrode 3, and the input electrode 5 and the output electrode 6
Are opposed to each other to form a wide opposed portion 5
a and 6a are formed. The input electrode, the output electrode and the U-shaped stripline resonator electrode are
It may be overlapped only with the open end side of the U-shaped stripline resonator electrode.

The capacitor electrode 7 faces the wide electrode portion 2 e at the open end of the U-shaped strip line 2, and one end of the capacitor electrode 7 is grounded on the side surface of the dielectric layer 4. Similarly, the other capacitor electrode 8 is opposed to the wide electrode portion 3 e at the open end of the U-shaped strip line 3, and one end of the capacitor electrode 8 is grounded on the side surface of the dielectric layer 4. The capacitance electrodes 7 and 8 are connected to the wide electrode portions 2e,
The electrode is larger than 3e, and its boundary is formed so as to overlap with sufficiently thin connection electrodes 2d and 3d as shown by the broken line in FIG.

The third dielectric layer 9 further includes an input electrode 5
Electrode 1 for forming a capacitor overlapping both the output electrode 6 and the output electrode 6
0 is formed. This overlapping state is as shown by the broken line in FIG.

A second dielectric layer is formed above and below the first dielectric layer.
Are laminated, a third dielectric layer is laminated above and below the dielectric layer, and a dielectric layer of a predetermined thickness is further interposed above and below the third dielectric layer,
A dielectric layer 12 on which an earth electrode 11 is formed is laminated on the upper and lower sides, and a protective dielectric layer 1 is formed on the upper earth electrode 12.
3 are stacked.

This dielectric layer is formed by forming a dielectric ceramic composition having a dielectric constant of about 8 into a sheet shape by a doctor blade, and each electrode is formed by screen-printing a conductive paste mainly composed of Ag. Formed. Then, after lamination and compression bonding, they are integrally fired at about 900 ° C., and then external electrodes 14, 15, 1
6, 17 are formed by printing. The external electrodes are an input external electrode 14, an output external electrode 15, and ground external electrodes 16, 17. The dielectric constant of the dielectric layer is desirably 7 to 40.

The bandpass filter characteristics of this embodiment are as follows:
As shown in FIG. As shown in FIG. 5, it has sufficient characteristics as a bandpass filter.

FIG. 6 shows an equivalent circuit diagram of this embodiment. U
The strip-shaped resonators 2 and 3 form equivalent circuit resonators K1 and K2, respectively, and the input electrode 5 and the U-shaped stripline resonator 2 face each other with a dielectric layer interposed therebetween. The capacitance C1 is formed, and the output electrode 6 and the U-shaped stripline resonator 3 are opposed to each other with the dielectric layer interposed therebetween, thereby forming the capacitance C2. Also,
The capacitor C4 is formed from the wide electrode portion 2e at the open end of the U-shaped stripline resonator 2 and the capacitor electrode 7, and the capacitor C5 is formed from the wide electrode portion 3e at the open end of the U-shaped stripline 3 and the capacitor electrode 8. Make up. A capacitor C3 is formed between the wide facing portions 5a and 6a of the input electrode 5 and the output electrode 6 facing each other, and between them and the capacitor forming electrode 10 of the third dielectric layer.

Of course, these constants can be adjusted by the area of the electrode, the thickness of the dielectric layer, and the like. For example, the adjustment can be made by partially increasing or decreasing the area of the electrode. By adjusting the capacitance of the capacitance electrodes C4 and C5, the center frequency of the filter characteristic can be adjusted by coupling the two U-shaped stripline resonators.
And the control of the pass band width and ripple.
The stripline resonators 2 and 3 are M-coupled (electromagnetically coupled).

The U-shaped strip lines 2, 3
Are strip line sections 2a, 3a having one end grounded and extending linearly, wide strip line sections 2c, 3c having a lower characteristic impedance, and strip line sections 2b, 3b having a higher characteristic impedance than those.
And these are strip line sections 2a, 3a,
Then, the strip lines 2b, 3b and the strip lines 2c, 3c are connected in series in this order.

By varying the width of the strip line, main characteristics such as the center frequency, insertion loss, and pass band width of the filter can be freely controlled.
A bandpass filter of 600 MHz to 2000 MHz could be constructed.

The wide opposing portions 5a, 6a of the input electrode 5 and the output electrode 6 are opposed to each other.
The opposition of 0 constitutes a capacitor C3 between input and output. Thus, a bandpass characteristic having a notch can be obtained, and the value of C3 can be adjusted to adjust the bandwidth to be wider or narrower.

Although the present invention has two second and third dielectric layers in the above embodiment, it is also possible to adopt a configuration in which only one is stacked on one side. Further, in the present invention, a configuration in which the third dielectric layer is removed may be employed.

[0027]

According to the present invention, a band-pass filter is formed by a U-shaped stripline resonator having one end grounded and the other end open, and an input / output electrode and a capacitor electrode facing the U-shaped stripline resonator with a dielectric layer interposed therebetween. And this U
The main characteristics of the filter can be freely controlled by the V-shaped stripline resonator and the capacitances C4 and C5, and the attenuation pole can be controlled by adjusting the input / output coupling capacitance. Can be secured. In addition, it is possible to suppress variation in characteristics due to stacking deviation, which is particularly useful for mobile phones and mobile communication devices.

[Brief description of the drawings]

FIG. 1 is an exploded view of an embodiment according to the present invention.

FIG. 2 is a plan view of a first dielectric layer according to one embodiment of the present invention.

FIG. 3 is a plan view of a second dielectric layer according to one embodiment of the present invention.

FIG. 4 is a perspective view of one embodiment according to the present invention.

FIG. 5 is a characteristic diagram of an example according to the present invention.

FIG. 6 is an equivalent circuit diagram of one embodiment according to the present invention.

FIG. 7 is an exploded perspective view of a conventional example.

FIG. 8 is an equivalent circuit diagram of a conventional example.

FIG. 9 is an exploded perspective view of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st dielectric layer 2, 3 U-shaped stripline resonator electrode 4 2nd dielectric layer 5 Input electrode 6 Output electrode 7, 8 Capacitance electrode 11 Earth electrode 9, 12, 13 Dielectric layer

Claims (2)

[Claims] At least two U-shaped stripline resonators each having one end grounded and the other end open are formed on a first dielectric layer, and the open end side of the U-shaped stripline resonator is formed. Has a wide electrode portion for forming a capacitor, the wide electrode portion and the open end of the U-shaped stripline resonator are connected by a connection electrode sufficiently narrower than the wide electrode portion, and on the second dielectric layer An input electrode, an output electrode, and a grounded capacitor electrode facing the wide electrode portion, wherein each of the input electrode and the output electrode is provided with at least one of the U-shaped stripline resonance electrodes. The first dielectric layer and the second dielectric layer are laminated so as to cross the U-shape of the container, and ground electrodes are arranged above and below the first dielectric layer and the second dielectric layer with a dielectric layer interposed therebetween. Stacked bandpass filter. 2. The semiconductor device according to claim 2, wherein said second dielectric layer is two,
2. The multilayer bandpass filter according to claim 1, wherein the V-shaped stripline resonator electrodes are arranged above and below the first dielectric layer on which the first dielectric layer is formed.